How to Write a Sample letter

This is the letter to convey my apology to the hospital from the nurse who worked there and relieved under maternity leave. First of all I should regret for my behaviour and I regret for it in a very precise manner. Actually I came out of the hospital by asking maternity leave. But the real thing is I could not cope up with the nurse work there. Also I could not complete the work in time. To reveal this only am writing this letter. I request you to apologise me for saying this. Since there are many things to be done and many things are yet to start I could not make it on time. But am sure if you award me one more chance or a kind of grace period to complete the work, I will get it to be done and will not let the hospital go down one more time.